Plain English Meaning
An aircraft built and approved to the FAA's normal set of rules for design, construction, and safety, with a regular airworthiness certificate. Most training aircraft, general aviation singles, and airliners fall into this group.
Full Definition
An aircraft that has been issued a standard airworthiness certificate by the FAA, indicating it was manufactured to an FAA-approved type design and conforms to that design in normal, utility, acrobatic, commuter, or transport category. These aircraft meet full FAA airworthiness standards and are not restricted to the limitations placed on , , restricted, or aircraft.